PSI or air fluctuations on the gauge

I've noticed depending on the weather the air guns I have will fluctuate what it displays on the air gauges from day to day even though I haven't used them
I was wondering if anybody else has experienced similar things with the air guns
Sometimes I will leave them in the truck but I was wondering people's thoughts on this specifically pertaining to notices in PSI based on the weather
The fluctuations I've seen have been minor but I've noticed them